The present invention relates to a correction method of a sticking phenomenon which appears in a self-luminous apparatus, a sticking phenomenon correction apparatus, a self-luminous apparatus in which a sticking phenomenon correction apparatus is incorporated, and a program for causing a computer incorporated in a self-luminous apparatus to execute a sticking correction process.
A flat panel display unit has spread widely in various products such as computer display units, portable terminal units, television sets and so forth. At present, while a liquid crystal display panel is used frequently, subjects of a limited angular field of view and a low responding speed still remain pointed out.
On the other hand, an organic EL display unit formed from self-luminous elements can overcome the subjects of the angular field of view and the responding speed described above and can achieve a form of a reduced thickness which eliminates a backlight, a high luminance and a high contrast. Therefore, the organic EL display unit is expected as a next generation display apparatus in place of a liquid crystal display unit.
Incidentally, it is commonly known that self-luminous elements including organic EL elements have a characteristic of deteriorating in accordance with the emitted light amount and the light emission time period thereof.
Meanwhile, the substance of an image to be displayed on a display unit is not uniform. Therefore, deterioration of self-luminous elements is likely to proceed locally. For example, deterioration of self-luminous elements in a time displaying region (fixed displaying region) proceeds more rapidly than that of self-luminous elements in the other displaying region (dynamic image displaying region).
The luminance of a self-luminous element whose deterioration has proceeded is relatively lower than that of self-luminous elements in the other displaying region. Generally, the phenomenon just described is called “sticking”. Local deterioration of self-luminous elements is hereinafter referred to as “sticking”.
Various methods are examined as improving measures against the sticking phenomenon. Some of such methods are disclosed in the following documents.
1. Japanese Patent Laid-open No. 2003-228329 (hereinafter referred to as Patent Document 1) discloses a method wherein input data to pixels which form a display panel are integrated for each of the pixels and integrated values of the pixels are subtracted from a maximum value of the input data to set correction amounts for the pixels. Further, Patent Document 1 discloses a method wherein, when the display panel is in a non-used state, each pixel is driven to emit light with a fixed luminance for a time period which increases in proportion to the magnitude of a correction amount therefore to make the displaying characteristics of the pixels uniform.
2. Japanese Patent Laid-open No. 2003-295827 (hereinafter referred to as Patent Document 2) discloses a method wherein display data and a display time period are stored only when a still picture is displayed and the integration amount ΔY·T obtained by integrating the difference ΔY between the display data and a maximum luminance and the time period T for which the still picture is displayed is set as correction data. Patent Document 2 further discloses a method wherein display for correction is executed only in a state wherein a cover is closed or in a non-used state of the apparatus to correct the sticking phenomenon.
3. Japanese Patent Laid-open No. 2000-132139 (hereinafter referred to as Patent Document 3) discloses a method wherein input data are integrated for each of pixels and the calculated integration value is converted into a correction value using a correction table. Further, Patent Document 3 discloses a method wherein input data to each of the pixels is corrected with the calculated correction value to decrease the visibility of the sticking phenomenon.
4. Japanese Patent Laid-open No. 2001-175221 (hereinafter referred to as Patent Document 4) discloses a method wherein a pixel whose luminance is most deteriorated is detected from among pixels and a correction value is determined so that luminance data of the other pixels are decreased with reference to the detected pixel. Further, Patent Document 4 discloses a method wherein the luminance data of the pixels are converted with the calculated correction value to decrease the visibility of the sticking phenomenon.
5. Japanese Patent Laid-open No. 2002-169509 (hereinafter referred to as Patent Document 5) discloses a method wherein the luminance of an entire panel is suppressed when a still picture is displayed or a reverse bias is applied to light emitting elements when the panel is in a standby mode to suppress unnecessary charge from being accumulated between electrodes of the light emitting elements thereby to lower the deterioration speed of the displaying characteristic to suppress appearance of the sticking phenomenon.
6. Japanese Patent Laid-open No. 2000-356981 (hereinafter referred to as Patent Document 6) discloses a correction method wherein the time period within which a panel emits light is accumulated and the luminance of the entire panel is suppressed in response to the accumulated time period. The correction method achieves reduction of the sticking phenomenon by suppressing the deterioration rate of the light emission characteristic.
7. Japanese Patent Laid-open No. 2003-308041 (hereinafter referred to as Patent Document 7) discloses a correction method wherein a moving picture region and a still picture region are decided on a screen and the luminance only in the still picture region is suppressed to delay appearance of the sticking phenomenon in the still picture region.
8. Japanese Patent Laid-open No. 2003-274315 (hereinafter referred to as Patent Document 8) discloses a correction method wherein an entire screen is displaced in a unit of a pixel in a certain cycle to cause a shading off effect to occur at the contour of a sticking portion to make the sticking phenomenon less conspicuous.